Wear-resistant rubber compositions, systems, and methods

ABSTRACT

This disclosure relates to wear-resistant rubber compositions, such as those, for example, comprising at least one hydroxy-terminated polybutadiene, at least one natural rubber, at least one polymerization accelerant; at least one sulfur; and at least one polybutadiene, wherein the wear-resistant rubber composition may have an effective cross-linking density of at least about 30×10 −5  moles/cm 3 .

FIELD OF THE DISCLOSURE

The present disclosure relates, in some embodiments, to wear-resistantrubber compositions and, more particularly, to wear-resistant rubbercompositions for use with mining equipment including, for example,wear-resistant lifter bar assemblies. The present disclosure alsorelates, in some embodiments, to systems and methods for damp shockabsorption by wear-resistant rubber compositions.

BACKGROUND OF THE DISCLOSURE

Wear-resistant rubber compositions may be used in automotive,construction, and mining industries. For example, in the miningindustry, a grinding mill comprising a cylindrical drum, grinding balls,an opening on each end, at least one lifter bar, and material to beground. As the grinding mill rotates about its z-axis, lifter bars liftthe material to be ground and the grinding balls, and then the materialto be ground and the grinding balls drop away from the lifter bars,wherein the material to be ground is ground between a combination of thegrinding balls, the inside walls of the cylindrical drum, and otherlifter bars. Lifter bars become worn through this grinding action andmust be regularly replaced, which increases monetary costs of millingoperations as well as decreases the fidelity of ground materials.

Alternatively, structures such as bridges and buildings require a shockabsorber and/or damper to damp shock impulses, thereby dissipatingkinetic energy created through movement of the structures themselves orthe environment surrounding the structures. Unabsorbed shock impulsesdamage structures directly, thereby creating costly repairs that must bemade to the structures. Similar shock absorption is needed in theautomotive industry, for example, to damp shock impulses from enginefunction and to absorb friction created through an automotive suspensionsystem.

SUMMARY

Accordingly, a need has arisen for improved wear-resistant rubbercompositions with advantageous processability and effectivecross-linking density.

The present disclosure relates, according to some embodiments, awear-resistant rubber composition may comprise at least onehydroxy-terminated polybutadiene; at least one natural rubber; at leastone polymerization accelerant; at least one sulfur; and at least onepolybutadiene, wherein the wear-resistant rubber composition may have aneffective cross-linking density of at least about 30×10⁻⁵ moles/cm³. Insome embodiments, a wear-resistant rubber composition may also compriseat least one antiozonant; at least one vulcanization inhibitor; at leastone silica; at least one processing additive; at least one couplingagent; or combinations thereof. A wear-resistant rubber composition mayalso comprise an organosilane additive; at least one peptizer; at leastone plasticizer; at least one carbon black; or combinations thereof,according to some embodiments. According to some embodiments, at leastone natural rubber may be present at a concentration ranging from about20 wt. % to about 70 wt. % of the wear-resistant rubber composition.

According to some embodiments, the present disclosure relates to awear-resistant rubber composition, wherein at least one polymerizationaccelerant may be selected from the group consisting of zinc oxide,stearic acid, N-cyclohexyl-2-benzothiazole sulfonamide, tetrabenzylthiuram disulfide. In some embodiments, at least one hydroxy-terminatedpolybutadiene may be present at a concentration ranging from about 1 wt.% to about 10 wt. % of the wear-resistant rubber composition. At leastone hydroxy-terminated polybutadiene may be present at a concentrationof about 2 wt. % of the wear-resistant rubber composition, in someembodiments. At least one polybutadiene may be present at aconcentration ranging from about 2 wt. % to about 20 wt. % of thewear-resistant rubber composition, according to some embodiments. Insome embodiments, at least one processing additive may be present at aconcentration ranging from about 1 wt. % to about 10 wt. % of thewear-resistant rubber composition. In some embodiments, a wear-resistantrubber composition may be used in a wear-resistant lifter bar assembly.A wear-resistant rubber composition may have an effective cross-linkingdensity of at least about 40×10⁻⁵ moles/cm³. According to someembodiments, a wear-resistant rubber composition may have an effectivecross-linking density of at least about 60×10⁻⁵ moles/cm³. In someembodiments, a wear-resistant rubber composition may wear from about 10%to about 40% over a period of time, the period of time may be selectedfrom the group consisting of about 1 week, about 3 weeks, about 7 weeks,about 14 weeks, about 21 weeks, and about 24 weeks. In some embodiments,a wear-resistant rubber composition wears at most about 30% over about24 weeks.

The present disclosure relates, in some embodiments, to a wear-resistantlifter bar assembly comprising at least one rack for fixing the wearresistant lifter bar to a cylindrical wall of a rotating drum of a mill;and at least one wear body comprising a wear resistant rubbercomposition, wherein the wear resistant rubber composition comprises: atleast one hydroxy-terminated polybutadiene; at least one natural rubber;at least one polymerization accelerant; at least one sulfur; and atleast one polybutadiene, wherein the wear-resistant rubber compositionwherein the wear-resistant rubber composition may have an effectivecross-linking density of at least about 30×10⁻⁵ moles/cm³. In someembodiments, a wear resistant rubber composition may comprise: at leastone antiozonant; at least one vulcanization inhibitor; at least onesilica; at least one processing additive; at least one coupling agent;or combinations thereof. According to some embodiments, a wear resistantrubber composition may comprise: an organosilane additive; at least onepeptizer; at least one plasticizer; at least one carbon black; orcombinations thereof. At least one natural rubber may be present at aconcentration ranging from about 20 wt. % to about 70 wt. % of thewear-resistant rubber composition, according to some embodiments. Insome embodiments, at least one polymerization accelerant may be selectedfrom the group consisting of zinc oxide, stearic acid,N-cyclohexyl-2-benzothiazole sulfonamide, tetrabenzyl thiuram disulfide.In some embodiments, at least one hydroxy-terminated polybutadiene maybe present at a concentration ranging from about 1 wt. % to about 10 wt.% of the wear-resistant rubber composition. According to someembodiments, at least one hydroxy-terminated polybutadiene may bepresent at a concentration of about 2 wt. % of the wear-resistant rubbercomposition. In some embodiments, at least one polybutadiene may bepresent at a concentration ranging from about 2 wt. % to about 20 wt. %of the wear-resistant rubber composition. At least one processingadditive may be present at a concentration ranging from about 1 wt. % toabout 10 wt. % of the wear-resistant rubber composition, in someembodiments. A wear-resistant rubber composition may have an effectivecross-linking density of at least about 40×10⁻⁵ moles/cm³. Awear-resistant rubber composition may have an effective cross-linkingdensity of at least about 60×10⁻⁵ moles/cm³, according to someembodiments of the disclosure. A wear-resistant rubber composition wearsfrom about 10% to about 40% over a period of time, the period of timeselected from the group consisting of about 1 week, about 3 weeks, about7 weeks, about 14 weeks, about 21 weeks, and about 24 weeks, accordingto some embodiments. In some embodiments, a wear-resistant rubbercomposition wears at most about 30% over about 24 weeks.

The present disclosure relates, according to some embodiments, to awear-resistant rubber composition comprising: at least onehydroxy-terminated polybutadiene; at least one natural rubber; at leastone polymerization accelerant; at least one sulfur; and at least onepolybutadiene, wherein the wear-resistant rubber composition may have aneffective cross-linking density of at least about 30×10⁻⁵ moles/cm³, andwherein the wear-resistant rubber composition wears from about 10% toabout 40% over a period of time, the period of time selected from thegroup consisting of about 1 week, about 3 weeks, about 7 weeks, about 14weeks, about 21 weeks, and about 24 weeks. In some embodiments, awear-resistant rubber composition may comprise: at least oneantiozonant; at least one vulcanization inhibitor; at least one silica;at least one processing additive; at least one coupling agent; orcombinations thereof. According to some embodiments, a wear-resistantrubber composition may comprise: an organosilane additive; at least onepeptizer; at least one plasticizer; at least one carbon black; orcombinations thereof.

In some embodiments, a wear-resistant rubber composition wears at mostabout 30% over about 24 weeks. In some embodiments, the presentdisclosure relates to a wear-resistant rubber composition that may beused in a wear-resistant lifter bar assembly.

The present disclosure relates, according to some embodiments, to awear-resistant shock absorber assembly comprising: an object withsufficient mass to benefit from shock absorption; and a wear-resistantrubber composition, wherein the wear-resistant rubber compositioncomprises: at least one hydroxy-terminated polybutadiene; at least onenatural rubber; at least one polymerization accelerant; at least onesulfur; and at least one polybutadiene, wherein the wear-resistantrubber composition may have an effective cross-linking density of atleast about 30×10⁻⁵ moles/cm³. In some embodiments, a wear-resistantshock absorber assembly may comprise: at least one antiozonant; at leastone vulcanization inhibitor; at least one silica; at least oneprocessing additive; at least one coupling agent; or combinationsthereof. According to some embodiments, a wear-resistant shock absorberassembly may comprise: an organosilane additive; at least one peptizer;at least one plasticizer; at least one carbon black; or combinationsthereof.

In some embodiments, at least one natural rubber may be present at aconcentration ranging from about 20 wt. % to about 70 wt. % of thewear-resistant rubber composition. According to some embodiments, atleast one polymerization accelerant may be selected from the groupconsisting of zinc oxide, stearic acid, N-cyclohexyl-2-benzothiazolesulfonamide, tetrabenzyl thiuram disulfide. In some embodiments, a tleast one hydroxy-terminated polybutadiene may be present at aconcentration ranging from about 1 wt. % to about 10 wt. % of thewear-resistant rubber composition. According to some embodiments, atleast one hydroxy-terminated polybutadiene may be present at aconcentration of about 2 wt. % of the wear-resistant rubber composition.In some embodiments, at least one polybutadiene may be present at aconcentration ranging from about 2 wt. % to about 20 wt. % of thewear-resistant rubber composition. In some embodiments, at least oneprocessing additive may be present at a concentration ranging from about1 wt. % to about 10 wt. % of the wear-resistant rubber composition.According to some embodiments, a wear-resistant rubber composition maybe used in a wear-resistant lifter bar assembly. According to someembodiments, a wear-resistant rubber composition may have an effectivecross-linking density of at least about 40×10⁻⁵ moles/cm³. According tosome embodiments, a wear-resistant rubber composition may have aneffective cross-linking density of at least about 60×10⁻⁵ moles/cm³. Insome embodiments, a wear-resistant rubber composition wears from about10% to about 40% over a period of time, the period of time selected fromthe group consisting of about 1 week, about 3 weeks, about 7 weeks,about 14 weeks, about 21 weeks, and about 24 weeks. According to someembodiments, a wear-resistant rubber composition wears at most about 30%over about 24 weeks. In some embodiments, a object with sufficient massto benefit from shock absorption comprises an automotive engine, abridge, a building, an automobile, a seismic attenuator, a vibrationdamping rubber bushing, and a shock absorption.

BRIEF DESCRIPTION OF THE DRAWINGS

The file of this patent contains at least one drawing executed in color.Copies of this patent with color drawing(s) will be provided by thePatent and Trademark Office upon request and payment of the necessaryfee.

Some embodiments of the disclosure may be understood by referring, inpart, to the present disclosure and the accompanying drawings, wherein:

FIG. 1 illustrates differing rheometer data for wear-resistant rubbercompositions with varying hydroxy-terminated polybutadieneconcentrations, according to specific example embodiments of thedisclosure;

FIG. 2 illustrates differing measured maximum torque values ofwear-resistant rubber compositions with varying hydroxy-terminatedpolybutadiene concentrations, according to specific example embodimentsof the disclosure;

FIG. 3 illustrates differing measured hardness values of wear-resistantrubber compositions with varying hydroxy-terminated polybutadieneconcentrations, according to specific example embodiments of thedisclosure;

FIG. 4 illustrates differing measured tensile strength values ofwear-resistant rubber compositions with varying hydroxy-terminatedpolybutadiene concentrations, according to specific example embodimentsof the disclosure;

FIG. 5 illustrates elongation measurement values across wear-resistantrubber compositions with varying hydroxy-terminated polybutadieneconcentrations, according to specific example embodiments of thedisclosure;

FIG. 6A illustrates lifter bar wear testing performed over a period offour weeks on lifter bars comprising wear-resistant rubber compositionsnot containing hydroxy-terminated polybutadiene, according to specificexample embodiments of the disclosure; and

FIG. 6B illustrates lifter bar wear testing performed on a period offour weeks on lifter bars comprising wear-resistant rubber compositionscomprising hydroxy-terminated polybutadiene, according to specificexample embodiments of the disclosure.

DETAILED DESCRIPTION

The present disclosure relates, in some embodiments, to wear-resistantrubber compositions. In some embodiments, a wear-resistant rubbercomposition may be used with mining, automotive, and industrialequipment, including, for example, damp shock absorbers and/or lifterbars. In wear-resistant rubber compositions comprising at least onesilica, a vacuole and/or empty space may form around the at least onesilica. In some embodiments, a vacuole and/or empty space around atleast one silica may be formed as a result of a weak filler polarityinteraction to a wear-resistant rubber composition matrix. According tosome embodiments, wear-resistant rubber compositions may comprise atleast one silane, wherein the presence of at least one silane may resultin strong filler to wear-resistant rubber composition matrix bonding. Insome embodiments, wear-resistant rubber compositions comprising at leastone hydroxy-terminated polybutadiene (e.g., Poly Bd R20LM) mayadvantageously have a strong bond between the filler and othercomponents of a wear-resistant rubber composition matrix. Ahydroxy-terminated polybutadiene may improve filler interaction with thewear-resistant rubber composition matrix. In some embodiments,wear-resistant rubber compositions comprising at least onehydroxy-terminated polybutadiene may prevent vacuole formation incompositions comprising at least one silica, wherein said compositionwould readily form vacuoles in the absence of the at least onehydroxy-terminated polybutadiene.

According to some embodiments, compositions comprising reinforcingfillers (e.g., silica) may also have an increased dynamic modulus ofrubber. Contribution of a filler to a dynamic modulus of rubber maycomprise strain-dependent modulus and strain independent modulus. Insome embodiments, a filler-filler interaction may contribute to a straindependent modulus, wherein increasing strain may decrease modulus. Insome embodiments, a Payne effect may be due to a partial reversebreakdown of filler-filler interactions within a filler network.

In some embodiments, wear-resistant rubber compositions comprising atleast one hydroxy-terminated polybutadiene (e.g., Poly Bd R20LM), maycomprise advantageous wear resistance. In some embodiments,wear-resistant rubber compositions comprising at least onehydroxy-terminated polybutadiene may have a low Payne-effect. Accordingto some embodiments, wear-resistant rubber compositions comprising atleast one hydroxy-terminated polybutadiene may have lower filler-fillerinteractions (i.e., Payne effects) in comparison to wear-resistantrubber compositions not containing at least one hydroxy-terminatedpolybutadiene. In some embodiments, having a low Payne-effect may allowwear-resistant rubber compositions to have advantageous wear resistancewhile also advantageously meeting processing requirements necessary toaccommodate the needs for industries comprising mining, oil and gas,automotive, and construction.

In some embodiments, a wear-resistant rubber composition may beadvantageously resistant to wear, wear comprising a resistance todegradation and/or erosion in the presence of at least one stress, theat least one stress comprising abrasion, high temperatures (e.g., atleast about 500° F.), low temperatures (e.g., at most about −40° F.),temperature fluctuations, high pressures (e.g., at least about 10000psi), low pressures (e.g., at most about 1×10⁻⁵ psi), pressurefluctuations, impact, or combinations thereof. According to someembodiments, wear resistance may comprise a resistance to degradationand/or erosion that may be caused through an interaction of awear-resistant rubber composition and an adjacent surface of anotherbody, wherein another body (e.g., a load) may comprise a solid, liquid,or gas. A wear-resistant rubber composition may be resistant to wearthat may be caused by at least one load, the at least one loadcomprising an impact load, a unidirectional sliding load, amulti-directional sliding load, a rolling load, or combination thereof.In some embodiments, a wear-resistant rubber composition may resist wearcomprising fretting wear (i.e., repeated cyclical contacting between twosurfaces), erosive wear, oxidation wear, corrosion wear, or combinationsthereof.

Wear-Resistant Rubber Compositions

In some embodiments, a wear-resistant rubber composition may comprise anelastomer, such as a thermoset elastomer capable of withstanding wear.As used herein, for example, an elastomer may comprise: natural rubber(NR), polyurethane, butadiene acrylonitrile copolymer, nitrile rubber,liquid polybutadiene (Liquid PBD), NBR, hydrogenated nitrile rubber,hydrogenated NBR, highly saturated nitrile, HNR, HNBR, carboxylated NBR(XNBR), chloroprene rubber (CR), ethylene propylene diene terpolymer(EPDM), acrylic rubber (ACM), styrene-butadiene rubber (SBRS,polybutadiene/butadiene rubber (BR), low acrylonitrile nitrile (a lowACN nitrile), synthetic polyisoprene, butyl rubbers (IIR),chlorosulphonated polyethylene (CSM), silicone, fluoro rubbers,perfluoro rubbers, tetrafluoro ethylene propylene rubber (FEPM), andcombinations thereof.

According to some embodiments, a wear-resistant rubber composition maycomprise at least one natural rubber (e.g., polyisoprene). In someembodiments, a wear-resistant rubber composition may comprise an atleast one natural rubber content of about 10 wt. %, or about 15 wt. %,or about 20 wt. %, or about 25 wt. %, or about 30 wt. %, or about 35 wt.%, or about 40 wt. %, or about 50 wt. %, or about 55 wt. %, or about 60wt. % of the wear-resistant rubber composition. In some embodiments,“about,” as used in the preceding sentence, includes plus or minus 5 wt.%. In some embodiments, a wear-resistant rubber composition may compriseabout 5 parts per hundred rubber (Phr) of at least one natural rubber,or about 20 Phr of at least one natural rubber, or about 25 Phr of atleast one natural rubber, or about 30 Phr of at least one naturalrubber, or about 35 Phr of at least one natural rubber, or about 40 Phrof at least one natural rubber, or about 45 Phr of at least one naturalrubber, or about 50 Phr of at least one natural rubber, or at leastabout 60 Phr of at least one natural rubber, or at least about 65 Phr ofat least one natural rubber, or at least about 70 Phr of at least onenatural rubber, or at least about 75 Phr of at least one natural rubber,or at least about 80 Phr of at least one natural rubber, or at leastabout 85 Phr of at least one natural rubber, or at least about 90 Phr ofat least one natural rubber. In some embodiments, “about,” as used inthe preceding sentence, includes plus or minus 5 Phr. In someembodiments, at least one natural rubber may comprise,cis-1,4-polyisoprene, trans-1,4-polyisoprene, or combinations thereof.In some embodiments, an addition of at least one natural rubber mayadvantageously provide resilience, enhanced dynamic properties with alow hysteresis loss, and/or good low temperature properties. Accordingto some embodiments, at least one natural rubber may comprise across-linking agent. In some embodiments, at least one natural rubbermay comprise a cross-linking agent content of about 1 Phr to about 20Phr.

In some embodiments, a wear-resistant rubber composition may comprise atleast one hydroxy-terminated polybutadiene (e.g., Poly BD R20LM, Poly BDR-45HTLO). According to some embodiments, a wear-resistant rubbercomposition may comprise an at least one hydroxy-terminatedpolybutadiene content of about 1 wt. %, or about 2 wt. %, or about 4 wt.%, or about 6 wt. %, or about 8 wt. %, or about 10 wt. %, or about 12wt. %, or about 14 wt. %, or about 16 wt. %, or about 18 wt. %, or about20 wt. % of the wear-resistant rubber composition. In some embodiments,“about,” as used in the preceding sentence, includes plus or minus 1 wt.%. In some embodiments, a wear-resistant rubber composition may compriseabout 1 Phr of at least one hydroxy-terminated polybutadiene, or about 2Phr of at least one hydroxy-terminated polybutadiene, or about 3 Phr ofat least one hydroxy-terminated polybutadiene, or about 4 Phr of atleast one hydroxy-terminated polybutadiene, or about 5 Phr of at leastone hydroxy-terminated polybutadiene, or about 6 Phr of at least onehydroxy-terminated polybutadiene, or about 6 Phr of at least onehydroxy-terminated polybutadiene, or about 7 Phr of at least onehydroxy-terminated polybutadiene, or about 8 Phr of at least onehydroxy-terminated polybutadiene, or about 9 Phr of at least onehydroxy-terminated polybutadiene, or about 10 Phr of at least onehydroxy-terminated polybutadiene. In some embodiments, “about,” as usedin the preceding sentence, includes plus or minus 2.5 Phr.

According to some embodiments, a wear-resistant composition comprisingat least one hydroxy-terminated polybutadiene may advantageously meetprocessing requirements necessary to accommodate the needs forindustries comprising mining, oil and gas, automotive, and construction.In some embodiments, processing may comprise curing, fabricating,extruding, calendaring, cutting, mixing, balancing, rolling, milling,granulating, shredding, squeezing, pelleting, packaging, drying,vulcanizing, tumbling, compounding, cleansing, coating, or combinationthereof. In some embodiments, a wear-resistant composition comprising atleast one hydroxy-terminated polybutadiene may have a lower Payne effectin comparison to a wear-resistant composition not containing at leastone hydroxy-terminated polybutadiene. According to some embodiments, awear-resistant rubber composition comprising at least onehydroxy-terminated polybutadiene may have a reduced deformation-inducedchange in a wear-resistant rubber composition microstructure incomparison to a wear-resistant rubber composition not containing atleast hydroxy-terminated polybutadiene. In some embodiments,deformation-induced change in a wear-resistant rubber compositionmicrostructure may cause frequency and/or amplitude dependent stiffeningof the wear-resistant rubber composition.

According to some embodiments, a Payne effect may be attributed todeformation-inducing changes and/or a breaking of at least onemicrostructure within a wear-resistant rubber composition, which may bedue to weak physical bond linking of an adjacent filler. In someembodiments, a filler may comprise at least one silica, at least onesilane, or combinations thereof. In some embodiments, increasing anamount of at least one filler may increase a Payne effect within awear-resistant rubber composition. In some embodiments, an addition ofat least one hydroxy-terminated polybutadiene to a wear-resistant rubbercomposition may advantageously build a robust linking process betweenthe wear-resistant rubber composition and at least one filler. Anaddition of at least one hydroxy-terminated polybutadiene to awear-resistant rubber composition may reduce a Payne effect of thewear-resistant rubber composition. In some embodiments, a robust linkingprocess between a wear-resistant rubber composition and at least onefiller may reduce interactions between the wear-resistant rubbercomposition and at least one filler, which may result in reducing aPayne effect in the wear-resistant rubber composition. In someembodiments, reducing a Payne effect in a wear-resistant rubbercomposition may increase a relative thermal stability of thewear-resistant rubber composition, may increase relative abrasionresistance of the wear-resistant rubber composition, or combinationsthereof. For example, a lifter bar and/or a mill liner comprising atleast one wear-resistant rubber composition with a reduced Payne effectmay have a relative increased useful tread life and/or consistentperformance, according to some embodiments of the disclosure. In someembodiments, a wear-resistant rubber composition with a reduced Payneeffect may be used to fabricate products with an increased abrasionresistance, the products comprising lifter bars, screen media, swellablepackers, and mill liners.

In some embodiments a wear-resistant rubber composition comprising atleast one hydroxy-terminated polybutadiene may further comprise a higherdensity of cross-linking (i.e., degree of cross-linking) in comparisonto a wear-resistant rubber composition that does not comprise at leastone hydroxy-terminated polybutadiene. According to some embodiments, awear-resistant rubber composition may comprise an effectivecross-linking density (ν_(e)) from about 30 to about 80×10⁻⁵ moles/cm³.In some embodiments, a wear-resistant rubber composition may comprise aneffective cross-linking density of about 30×10⁻⁵ moles/cm³, or of about35×10⁻⁵ moles/cm³, 40×10⁻⁵ moles/cm³, or of about 45×10⁻⁵ moles/cm³, orof about 50×10⁻⁵ moles/cm³, or of about 55×10⁻⁵ moles/cm³, or of about60×10⁻⁵ moles/cm³, or of about 65×10⁻⁵ moles/cm³, or of about 70×10⁻⁵moles/cm³, or of about 75×10⁻⁵ moles/cm³, or of about 80×10⁻⁵ moles/cm³.In some embodiments, “about,” as used in the preceding sentence,includes plus or minus 5×10⁻⁵ moles/cm³. For example, a wear-resistantrubber composition may comprise an effective cross-linking density of≥about 30×10⁻⁵ moles/cm³, or ≥about 35×10⁻⁵ moles/cm³, or ≥about 40×10⁻⁵moles/cm³, or ≥about 45×10⁻⁵ moles/cm³, or ≥about 50×10⁻⁵ moles/cm³, or≥about 55×10⁻⁵ moles/cm³, or ≥about 60×10⁻⁵ moles/cm³, or ≥about 65×10⁻⁵moles/cm³, or ≥about 70×10⁻⁵ moles/cm³, or ≥about 75×10⁻⁵ moles/cm³, or≥about 80×10⁻⁵ moles/cm³. In some embodiments, “about,” as used in thepreceding sentence, includes plus or minus 5×10⁻⁵ moles/cm³, accordingto some embodiments.

According to some embodiments, a wear-resistant rubber composition maycomprise at least one silica (e.g., Hisil 190G—Silica) content of about5 wt. %, of about 10 wt. %, or of about 15 wt. %, or of about 20 wt. %,or of about 25 wt. %, or of about 30 wt. %, or of about 35 wt. %, or ofabout 40 wt. % of the wear-resistant rubber composition. In someembodiments, “about,” as used in the preceding sentence, includes plusor minus 5 wt. %. In some embodiments, a wear-resistant rubbercomposition may comprise about 40 Phr of at least one silica, or about45 Phr of at least one silica, or about 50 Phr of at least one silica,or about 55 Phr of at least one silica, or about 60 Phr of at least onesilica, or about 65 Phr of at least one silica, or about 70 Phr of atleast one silica. In some embodiments, “about,” as used in the precedingsentence, includes plus or minus 0.2 Phr. In some embodiments, theaddition of at least one silica may advantageously contribute topreventing based wear resistance and may reinforce a wear-resistantrubber composition. In some embodiments, at least one silica maycomprise a high surface area silica.

According to some embodiments, a wear-resistant rubber composition maycomprise at least one polybutadiene (e.g., high cis polybutadienerubber, low cis polybutadiene rubber). In some embodiments, awear-resistant rubber composition may comprise an at least onepolybutadiene content of about 1 wt. %, or about 2 wt. %, or about 4 wt.%, or about 6 wt. %, or about 8 wt. %, or about 10 wt. %, or about 12wt. %, or about 14 wt. %, or about 16 wt. %, or about 18 wt. %, or about20 wt. % of the wear-resistant rubber composition. In some embodiments,“about,” as used in the preceding sentence, includes plus or minus 1 wt.%. In some embodiments, a wear-resistant rubber composition may compriseabout 1 Phr of at least one polybutadiene, or about 5 Phr of at leastone polybutadiene, or about 10 Phr of at least one polybutadiene, orabout 15 Phr of at least one polybutadiene, or about 20 Phr of at leastone polybutadiene, or about 25 Phr of at least one polybutadiene, orabout 30 Phr of at least one polybutadiene, or about 35 Phr of at leastone polybutadiene, or about 40 Phr of at least one polybutadiene, orabout 45 Phr of at least one polybutadiene. In some embodiments,“about,” as used in the preceding sentence, includes plus or minus 5Phr. In some embodiments, a high cis polybutadiene may be characterizedby a high proportion of cis (e.g., at least about 90% cis). In someembodiments, a low cis polybutadiene may be characterized by lowproportion of cis (e.g., at most about 40% cis). In some embodiments, atleast one polybutadiene may comprise a high vinyl polybutadiene (e.g.,at least about 70% vinyl). In some embodiments, adding at least onepolybutadiene to a wear-resistant rubber composition may improvemechanical strength, stability, and/or may contribute towear-resistance. According to some embodiments, at least onepolybutadiene may comprise at least one hydrolyzed HLT polybutadiene.

In some embodiments, a wear-resistant rubber composition may alsocomprise a cement, a Portland cement, and one or more reactive fillermaterials, such as cement, cementations material, metal oxide, andmixtures thereof, which react and swell upon contact with water. In someembodiments, a wear-resistant rubber composition may stiffen uponcontact with water. In some embodiments, a cement may result inimprovements in the physical properties of the rubber, such as increasedvolume and increased modulus. For example, a filler may be a reactivefiller, a reinforcing reactive filler, a sealing system, a cementclinker, a silicate, a aluminate, a ferrite and/or combinations thereof.

According to some embodiments, a wear-resistant rubber composition maycomprise at least one peptizer (e.g., zinc stearate, Struktol A60). Insome embodiments, a wear-resistant rubber composition may comprise atleast one peptizer content of about 0.1 wt. %, or about 0.2 wt. %, orabout 0.3 wt. %, or about 0.4 wt. %, or about 0.5 wt. %, or about 0.6wt. %, or about 0.7 wt. %, or about 0.8 wt. %, or about 0.9 wt. %, orabout 1.0 wt. %, or about 1.25 wt. %, or about 1.5 wt. % of thewear-resistant rubber composition. In some embodiments, “about,” as usedin the preceding sentence, includes plus or minus 0.1 wt. %. In someembodiments, a wear-resistant rubber composition may comprise about 5Phr of at least one peptizer, or about 0.4 Phr of at least one peptizer,or about 0.6 Phr of at least one peptizer, or about 0.8 Phr of at leastone peptizer, or about 1.0 Phr of at least one peptizer, or about 1.2Phr of at least one peptizer, or about 1.4 Phr of at least one peptizer,or about 1.6 Phr of at least one peptizer, or about 1.8 Phr of at leastone peptizer, or about 2 Phr, or about 2.2 Phr, or about 2.4 Phr, orabout 2.6 Phr, or about 2.8 Phr, or about 3.0 Phr of at least onepeptizer. In some embodiments, “about,” as used in the precedingsentence, includes plus or minus 0.2 Phr. In some embodiments, at leastone peptizer may comprise at least one physical peptizer, at leastchemical peptizer, or combinations thereof. According to someembodiments, a peptizer may facilitate filler incorporation, facilitatedispersion of compounding materials, improve elastomer blends, reduceprocessing temperatures, improve flow properties, enhance building tack,or combinations thereof.

In some embodiments, a wear-resistant rubber composition may comprise atleast one coupling agent (e.g., Bis[3-(triethoxysilyl)propyl]tetrasulfide, SI-69, 1-Methoxy-2-propoxy silane, methyltriethoxysilane). In some embodiments, a wear-resistant rubber composition maycomprise an at least one coupling agent content of about 1 wt. %, orabout 2 wt. %, or about 4 wt. %, or about 6 wt. %, or about 8 wt. %, orabout 10 wt. %, or about 12 wt. %, or about 14 wt. %, or about 16 wt. %,or about 18 wt. %, or about 20 wt. % of the wear-resistant rubbercomposition. In some embodiments, “about,” as used in the precedingsentence, includes plus or minus 1 wt. %. In some embodiments, awear-resistant rubber composition may comprise about 1 Phr of at leastone coupling agent, or about 2 Phr of at least one coupling agent, orabout 2 Phr of at least one coupling agent, or about 4 Phr of at leastone coupling agent, or about 6 Phr of at least one coupling agent, orabout 8 Phr of at least one coupling agent, or about 10 Phr of at leastone coupling agent, or about 12 Phr of at least one coupling agent, orabout 14 Phr of at least one coupling agent, or about 16 Phr of at leastone coupling agent, or about 18 Phr of at least one coupling agent, orabout 20 Phr of at least one coupling agent. In some embodiments,“about,” as used in the preceding sentence, includes plus or minus 2.5Phr. According to some embodiments, at least one coupling agent maycomprise bis (triethoxyl propyl) tetrasulfide (TESPT). In someembodiments, inclusion of at least one coupling agent may provide highercompound modulus, lower hysteresis, improved compression set, and maycontribute to wear-resistance. Inclusion of at least one coupling agentmay increase bonding between a silica and at least one wear-resistantrubber composition, which may contribute to wear-resistant properties.

In some embodiments, a wear-resistant rubber composition may alsocomprise at least one antiozonant (e.g., Luxco 2085,N-(1,3-Dimethylbutyl)-N′-phenyl-phenylenediamine (Santoflex 6PPD)). Insome embodiments, an antiozonant may comprise phenylenediamines (e.g.,N-(1,3-Dimethylbutyl)-N′-phenyl-phenylenediamine), diureas (e.g.,ethylene diurea), and paraffin waxes. In some embodiments, awear-resistant rubber composition may comprise an at least oneantiozonant content of about 0.1 wt. %, or about 0.2 wt. %, or about 0.4wt. %, or about 0.6 wt. %, or about 0.8 wt. %, or about 1.0 wt. %, orabout 1.2 wt. %, or about 1.4 wt. %, or about 1.6 wt. %, or about 1.8wt. %, or about 2.0 wt. % of the wear-resistant rubber composition. Insome embodiments, “about,” as used in the preceding sentence, includesplus or minus 0.1 wt. %. In some embodiments, a wear-resistant rubbercomposition may comprise about 1 Phr of at least one antiozonant, orabout 2 Phr of at least one antiozonant, or about 2 Phr of at least oneantiozonant, or about 4 Phr of at least one antiozonant, or about 6 Phrof at least one antiozonant, or about 8 Phr of at least one antiozonant,or about 10 Phr of at least one antiozonant, or about 12 Phr of at leastone antiozonant. In some embodiments, “about,” as used in the precedingsentence, includes plus or minus 1 Phr. According to some embodiments,an antiozonant may protect the wear-resistant rubber composition andfrom ozone.

In some embodiments, a wear-resistant rubber composition may comprise atleast one plasticizer (e.g., Tarene 30) for rubber products, such asphthalate esters (e.g., dioctyl phthalate), trimellitates, sebacates,adipates, terephthalates, benzoates, dibenzoates, organophosphates,gluterates, or azelates. In some embodiments, a wear-resistant rubbercomposition may comprise an at least one plasticizer content of about0.1 wt. %, or about 0.2 wt. %, or about 0.4 wt. %, or about 0.6 wt. %,or about 0.8 wt. %, or about 1.0 wt. %, or about 1.2 wt. %, or about 1.4wt. %, or about 1.6 wt. %, or about 1.8 wt. %, or about 2.0 wt. % of thewear-resistant rubber composition. In some embodiments, “about,” as usedin the preceding sentence, includes plus or minus 0.1 wt. %. In someembodiments, a wear-resistant rubber composition may comprise about 1Phr of at least one plasticizer, or about 2 Phr of at least oneplasticizer, or about 2 Phr of at least one plasticizer, or about 4 Phrof at least one plasticizer, or about 6 Phr of at least one plasticizer,or about 8 Phr of at least one plasticizer, or about 10 Phr of at leastone plasticizer, or about 12 Phr of at least one plasticizer. In someembodiments, “about,” as used in the preceding sentence, includes plusor minus 1 Phr. In some embodiments, a plasticizer may improve overallflexibility, low temperature properties and high temperature agingstability of a wear-resistant rubber composition.

In some embodiments, a wear-resistant rubber composition may comprise amaterial to reinforce a rubber compound to improve physical propertiesand/or color the product, such as pigments or carbon black (e.g., N-550,N326). According to some embodiments, a wear-resistant rubbercomposition may comprise a carbon black (e.g., Carbon black N234 ISAFHS, N326 Black) content of about 0.1 wt. %, or about 0.2 wt. %, or about0.4 wt. %, or about 0.6 wt. %, or about 0.8 wt. %, or about 1.0 wt. %,or about 1.2 wt. %, or about 1.4 wt. %, or about 1.6 wt. %, or about 1.8wt. %, or about 2.0 wt. % of the wear-resistant rubber composition. Insome embodiments, “about,” as used in the preceding sentence, includesplus or minus 0.1 wt. %. In some embodiments, a wear-resistant rubbercomposition may comprise about 1 Phr of at least one carbon black, orabout 2 Phr of at least one carbon black, or about 2 Phr of at least onecarbon black, or about 4 Phr of at least one carbon black, or about 6Phr of at least one carbon black, or about 8 Phr of at least one carbonblack, or about 10 Phr of at least one carbon black, or about 12 Phr ofat least one carbon black. In some embodiments, “about,” as used in thepreceding sentence, includes plus or minus 1 Phr.

In some embodiments, a wear-resistant rubber composition may comprise atleast one vulcanization inhibitor. In some embodiments, a vulcanizationinhibitor may comprise a phthalimide (e.g., cyclohexylthiophthalimide),diureas (e.g., ethylene diurea), and paraffin waxes. According to someembodiments, a wear-resistant rubber composition may comprise an atleast one vulcanization inhibitor content of about 0.1 wt. %, or about0.2 wt. %, or about 0.4 wt. %, or about 0.6 wt. %, or about 0.8 wt. %,or about 1.0 wt. %, or about 1.2 wt. %, or about 1.4 wt. %, or about 1.6wt. %, or about 1.8 wt. %, or about 2.0 wt. % of the wear-resistantrubber composition. In some embodiments, “about,” as used in thepreceding sentence, includes plus or minus 0.1 wt. %. In someembodiments, a wear-resistant rubber composition may comprise about 1Phr of at least one vulcanization inhibitor, or about 2 Phr of at leastone vulcanization inhibitor, or about 2 Phr of at least onevulcanization inhibitor, or about 4 Phr of at least one vulcanizationinhibitor, or about 6 Phr of at least one vulcanization inhibitor, orabout 8 Phr of at least one vulcanization inhibitor, or about 10 Phr ofat least one vulcanization inhibitor, or about 12 Phr of at least onevulcanization inhibitor. In some embodiments, “about,” as used in thepreceding sentence, includes plus or minus 1 Phr. In some embodiments,at least one vulcanization inhibitor may prevent scorch and preventpremature vulcanization in a wear-resistant rubber composition. In someembodiments, at least one vulcanization inhibitor may compriseN-(cyclohexylthio) phthalimide (CTP crystals).

According to some embodiments, a wear-resistant rubber composition maycomprise at least one polymerization accelerant, the at least onepolymerization accelerant comprising stearic acid,N-cyclohexyl-2-benzothiazole sulfonamide (CBS), tetrabenzyl thiuramdisulfide (TBzTd), zinc oxide, or combinations thereof. According tosome embodiments, a wear-resistant rubber composition may comprise an atleast one polymerization accelerant content of about 0.1 wt. %, or about0.2 wt. %, or about 0.4 wt. %, or about 0.6 wt. %, or about 0.8 wt. %,or about 1.0 wt. %, or about 1.2 wt. %, or about 1.4 wt. %, or about 1.6wt. %, or about 1.8 wt. %, or about 2 wt. %, or about 4 wt. %, or about5 wt. %, or about 6 wt. %, or about 8 wt. %, or about 10 wt. % of thewear-resistant rubber composition. In some embodiments, “about,” as usedin the preceding sentence, includes plus or minus 0.1 wt. %. In someembodiments, a wear-resistant rubber composition may comprise about 1Phr of at least one polymerization accelerant, or about 2 Phr of atleast one polymerization accelerant, or about 2 Phr of at least onepolymerization accelerant, or about 4 Phr of at least one polymerizationaccelerant, or about 6 Phr of at least one polymerization accelerant, orabout 8 Phr of at least one polymerization accelerant, or about 10 Phrof at least one polymerization accelerant, or about 12 Phr of at leastone polymerization accelerant. In some embodiments, “about,” as used inthe preceding sentence, includes plus or minus 1 Phr. In someembodiments, polymerization accelerants may increase the rate ofpolymerization in a wear-resistant rubber composition.

According to some embodiments, a wear-resistant rubber composition maycomprise at least one sulfur (e.g., Sulfur RM). According to someembodiments, a wear-resistant rubber composition may comprise an atleast one sulfur at a content of about 0.1 wt. %, of about 0.2 wt. %, orof about 0.3 wt. %, or of about 0.4 wt. %, or of about 0.6 wt. %, or ofabout 0.8 wt. %, or of about 1.0 wt. %, or of about 1.2 wt. %, or ofabout 1.4 wt. %, or of about 1.6 wt. %, or of about 1.8 wt. %, or ofabout 2 wt. %, or of about 3 wt. %, or of about 5 wt. %, or of about 10wt. % of the wear-resistant rubber composition. In some embodiments,“about,” as used in the preceding sentence, includes plus or minus 0.25wt. %. In some embodiments, a wear-resistant rubber composition maycomprise about 0.8 parts per hundred rubber (Phr) of at least onesulfur, or about 1.0 Phr of at least one sulfur, or about 1.2 Phr of atleast one sulfur, or about 1.4 Phr of at least one sulfur, or about 1.6Phr of at least one sulfur, or about 1.8 Phr of at least one sulfur, orabout 2.0 Phr of at least one sulfur, or about 2.2 Phr of at least onesulfur, or about 2.4 Phr of at least one sulfur, or about 2.6 Phr of atleast one sulfur, or about 2.8 Phr of at least one sulfur, or about 3.0Phr of at least one sulfur, or about 3.5 Phr of at least one sulfur, orabout 4.0 Phr of at least one sulfur. In some embodiments, “about,” asused in the preceding sentence, includes plus or minus 0.2 Phr.

In some embodiments, a wear-resistant rubber composition may comprise atleast one processing additive (e.g., Struktol HT 207, lard, C₈-C₂₉ fattyacids, straight chained fatty acids, branched chain fatty acids). Insome embodiments, a wear-resistant rubber composition may comprise atleast one processing additive at a content of about 0.1 wt. %, of about0.2 wt. %, or of about 0.3 wt. %, or of about 0.4 wt. %, or of about 0.6wt. %, or of about 0.8 wt. %, or of about 1.0 wt. %, or of about 1.2 wt.%, or of about 1.4 wt. %, or of about 1.6 wt. %, or of about 1.8 wt. %,or of about 2 wt. %, or of about 3 wt. %, or of about 5 wt. %, or ofabout 10 wt. % of the wear-resistant rubber composition. In someembodiments, “about,” as used in the preceding sentence, includes plusor minus 0.25 wt. %. In some embodiments, a wear-resistant rubbercomposition may comprise about 0.8 parts per hundred rubber (Phr) of atleast one sulfur, or about 1.0 Phr of at least one sulfur, or about 1.2Phr of at least one sulfur, or about 1.4 Phr of at least one sulfur, orabout 1.6 Phr of at least one sulfur, or about 1.8 Phr of at least onesulfur, or about 2.0 Phr of at least one sulfur, or about 2.2 Phr of atleast one sulfur, or about 2.4 Phr of at least one sulfur, or about 2.6Phr of at least one sulfur, or about 2.8 Phr of at least one sulfur, orabout 3.0 Phr of at least one sulfur, or about 3.5 Phr of at least onesulfur, or about 4.0 Phr of at least one sulfur. In some embodiments,“about,” as used in the preceding sentence, includes plus or minus 0.2Phr. In some embodiments, a processing additive may promote compositiondispersion and reduce agglomeration.

In some embodiments, a wear-resistant rubber composition may comprise atleast one antioxidant (e.g., methyl methacrylate butadiene styrene).According to some embodiments, a wear-resistant rubber composition maycomprise an at least one antioxidant at a content of about 0.1 wt. %, ofabout 0.2 wt. %, or of about 0.3 wt. %, or of about 0.4 wt. %, or ofabout 0.6 wt. %, or of about 0.8 wt. %, or of about 1.0 wt. %, or ofabout 1.2 wt. %, or of about 1.4 wt. %, or of about 1.6 wt. %, or ofabout 1.8 wt. %, or of about 2 wt. %, or of about 3 wt. %, or of about 5wt. %, or of about 10 wt. % of the wear-resistant rubber composition. Insome embodiments, “about,” as used in the preceding sentence, includesplus or minus 0.25 wt. %. In some embodiments, a wear-resistant rubbercomposition may comprise about 0.8 parts per hundred rubber (Phr) of atleast one antioxidant, or about 1.0 Phr of at least one antioxidant, orabout 1.2 Phr of at least one antioxidant, or about 1.4 Phr of at leastone antioxidant, or about 1.6 Phr of at least one antioxidant, or about1.8 Phr of at least one antioxidant, or about 2.0 Phr of at least oneantioxidant, or about 2.2 Phr of at least one antioxidant, or about 2.4Phr of at least one antioxidant, or about 2.6 Phr of at least oneantioxidant, or about 2.8 Phr of at least one antioxidant, or about 3.0Phr of at least one antioxidant, or about 3.5 Phr of at least oneantioxidant, or about 4.0 Phr of at least one antioxidant. In someembodiments, “about,” as used in the preceding sentence, includes plusor minus 0.2 Phr. In some embodiments, at least one antioxidant mayprotect a wear-resistant rubber composition from degradation caused byoxygen.

In some embodiments, a wear-resistant rubber composition may comprise atleast one antidegradant (e.g., 2,2,4-Trimethyl-1,2-dihydroquinoline(TMQ)). According to some embodiments, a wear-resistant rubbercomposition may comprise an at least one antidegradant at a content ofabout 0.1 wt. %, of about 0.2 wt. %, or of about 0.3 wt. %, or of about0.4 wt. %, or of about 0.6 wt. %, or of about 0.8 wt. %, or of about 1.0wt. %, or of about 1.2 wt. %, or of about 1.4 wt. %, or of about 1.6 wt.%, or of about 1.8 wt. %, or of about 2 wt. %, or of about 3 wt. %, orof about 5 wt. %, or of about 10 wt. % of the wear-resistant rubbercomposition. In some embodiments, “about,” as used in the precedingsentence, includes plus or minus 0.25 wt. %. In some embodiments, awear-resistant rubber composition may comprise about 0.8 parts perhundred rubber (Phr) of at least one antidegradant, or about 1.0 Phr ofat least one antidegradant, or about 1.2 Phr of at least oneantidegradant, or about 1.4 Phr of at least one antidegradant, or about1.6 Phr of at least one antidegradant, or about 1.8 Phr of at least oneantidegradant, or about 2.0 Phr of at least one antidegradant, or about2.2 Phr of at least one antidegradant, or about 2.4 Phr of at least oneantidegradant, or about 2.6 Phr of at least one antidegradant, or about2.8 Phr of at least one antidegradant, or about 3.0 Phr of at least oneantidegradant, or about 3.5 Phr of at least one antidegradant, or about4.0 Phr of at least one antidegradant. In some embodiments, “about,” asused in the preceding sentence, includes plus or minus 0.2 Phr. In someembodiments, at least one antidegradant may protect a wear-resistantrubber composition from degradation caused by factors, the factorscomprising heat, oxygen, light, and humidity.

According to some embodiments, a wear-resistant rubber composition maycomprise a hydrogenated nitrile butadiene rubber (e.g., HNBR Zetpol2030L, Therban 3496) content of about 0.5 wt. %, of about 1 wt. %, or ofabout 2 wt. %, or of about 3 wt. %, or of about 4 wt. %, or of about 5wt. %, or of about 6 wt. %, or of about 7 wt. %, or of about 8 wt. %, orof about 9 wt. %, or of about 10 wt. %, or of about 15 wt. % of thewear-resistant rubber composition. In some embodiments, “about,” as usedin the preceding sentence, includes plus or minus 2 wt. %.

According to some embodiments, a wear-resistant rubber composition maycomprise a styrene-butadiene rubber (e.g., 1502 SBR) content of about 5wt. %, of about 10 wt. %, or of about 15 wt. %, or of about 20 wt. %, orof about 25 wt. %, or of about 30 wt. %, or of about 35 wt. %, or ofabout 40 wt. %, or of about 45 wt. % of the wear-resistant rubbercomposition. In some embodiments, “about,” as used in the precedingsentence, includes plus or minus 5 wt. %.

According to some embodiments, a wear-resistant rubber composition maycomprise a low ACN nitrile (e.g., Perbunan 1846 F) content of about 5wt. %, of about 10 wt. %, or of about 15 wt. %, or of about 20 wt. %, orof about 25 wt. %, or of about 30 wt. %, or of about 35 wt. %, or ofabout 40 wt. %, or of about 45 wt. % of the wear-resistant rubbercomposition. In some embodiments, “about,” as used in the precedingsentence, includes plus or minus 5 wt. %.

In some embodiments, a wear-resistant rubber composition may alsocomprise at least one tackifier. In some embodiments, a tackifier maycomprise resins (i.e., hydrocarbon resins, phenolic-formaldehyde resin,coumarone-indene resin, and Struktol Koresin). According to someembodiments, a tackifier may result in an increase of tack (e.g.,stickiness of the surface). According to some embodiments, awear-resistant rubber composition may comprise at least one tackifier(e.g., Struktol Koresin) in a content of about 0.1 wt. %, of about 0.2wt. %, or of about 0.3 wt. %, or of about 0.4 wt. %, or of about 0.5 wt.%, or of about 0.6 wt. %, or of about 0.7 wt. %, or of about 0.8 wt. %,or of about 0.9 wt. %, or of about 1.0 wt. %, or of about 1.25 wt. %, orof about 1.5 wt. % of the wear-resistant rubber composition. In someembodiments, “about,” as used in the preceding sentence, includes plusor minus 0.25 wt. %.

In some embodiments, a wear-resistant rubber composition may alsocomprise a vulcanization accelerant. In some embodiments, avulcanization accelerant may comprise aldehyde amines, guanidines,thiazoles, thiophosphates, sulfonamides, thioureas, thiuram,dithiocarbamates, xanthanes. In some embodiments, a vulcanizationaccelerant may comprise tetramethyl thiuram disulfide,mercaptobenzthiazole disulfide, tetramethyl thiuram monosulfide,dipentamethylene thiuram, zinc chloride, tetrabenzylthiuram disulfide,or combinations thereof. According to some embodiments, a tackifier mayresult in an increase of vulcanization speed and may permitvulcanization to progress at lower temperatures.

According to some embodiments, a wear-resistant rubber composition maycomprise a vulcanization accelerant (e.g., MBTS, Thanecure ZM) contentof about 0.8 wt. %, of about 1.0 wt. %, or of about 1.2 wt. %, or ofabout 1.4 wt. %, or of about 1.6 wt. %, or of about 1.8 wt. %, or ofabout 2.0 wt. %, or of about 2.2 wt. %, or of about 2.4 wt. %, or ofabout 2.6 wt. %, or of about 2.8 wt. %, or of about 3.0 wt. % of thewear-resistant rubber composition. In some embodiments, “about,” as usedin the preceding sentence, includes plus or minus 0.2 wt. %. In someembodiments, a wear-resistant rubber composition may comprise about 0.8parts per hundred rubber (Phr) of at least one vulcanization accelerant,or about 1.0 Phr of at least one vulcanization accelerant, or about 1.2Phr of at least one vulcanization accelerant, or about 1.4 Phr of atleast one vulcanization accelerant, or about 1.6 Phr of at least onevulcanization accelerant, or about 1.8 Phr of at least one vulcanizationaccelerant, or about 2.0 Phr of at least one vulcanization accelerant,or about 2.2 Phr of at least one vulcanization accelerant, or about 2.4Phr of at least one vulcanization accelerant, or about 2.6 Phr of atleast one vulcanization accelerant, or about 2.8 Phr of at least onevulcanization accelerant, or about 3.0 Phr of at least one vulcanizationaccelerant, or about 3.5 Phr of at least one vulcanization accelerant,or about 4.0 Phr of at least one vulcanization accelerant. In someembodiments, “about,” as used in the preceding sentence, includes plusor minus 0.25 Phr.

According to some embodiments, a wear-resistant rubber composition maycomprise a peroxide (e.g., Dicup 40KE Peroxide, hydrogen peroxide, 40%Dicumyl Peroxide) content of about 0.1 wt. %, of about 0.2 wt. %, or ofabout 0.3 wt. %, or of about 0.4 wt. %, or of about 0.5 wt. %, or ofabout 0.6 wt. %, or of about 0.7 wt. %, or of about 0.8 wt. %, or ofabout 0.9 wt. %, or of about 1.0 wt. %, or of about 1.25 wt. %, or ofabout 1.5 wt. % of the wear-resistant rubber composition. In someembodiments, “about,” as used in the preceding sentence, includes plusor minus 0.1 wt. %.

In some specific example embodiments, a wear-resistant rubbercomposition may comprise the following composition, as shown in Table 1(Composition A):

TABLE 1 Composition of Degradable Composition A Material DescriptionParts Per Hundred (Phr) Natural Rubber (e.g., Polyisoprene, SVR10) 30-90(e.g., 70.5) Polybutadiene (e.g., high cis polybutadiene) 10-40 (e.g.,30.7) hydroxy-terminated polybutadiene (e.g., 1-10 (e.g., 5) Poly BdR20LM) Peptizer (e.g., Struktol A60) 1-10 (e.g., 1.8) Silica (e.g.,Hisil 190G) 30-80 (e.g., 60.05) Coupling agent (e.g., SI-69) 1-10 (e.g.,8.2) Antiozonant (e.g., Luxco 2085) 1-10 (e.g., 1.8) Polymerizationaccelerant (e.g., Stearic acid) 1-10 (e.g., 1.8) Plasticizer (e.g.,Tarene 30) 1-10 (e.g., 2.5) Processing additive (e.g., Struktol HT 207)1-10 (e.g., 2.8) Antiozonant (e.g., 6PPD) 1-10 (e.g., 1.3)Polymerization accelerant (e.g., CBS) 1-10 (e.g., 1.3) Polymerizationaccelerant (e.g., TbzTD) 01-1 (e.g., 0.24) Sulfur 0.1-2 (e.g., 0.9)Carbon black (e.g., N-326) 0.1-5 (e.g., 1.2) Vulcanization inhibitor(e.g., PVI) 0.1-5 (e.g., 0.6) Polymerization accelerant (e.g., zincoxide) 1-10 (e.g., 7)

In some specific example embodiments, a wear-resistant rubbercomposition may comprise the following composition, as shown in Table 2(Composition B):

TABLE 2 Composition of Degradable Composition B Material DescriptionParts Per Hundred (Phr) Natural Rubber (e.g., Polyisoprene, SVR10) 30-90(e.g., 76.05) Polybutadiene (e.g., high cis polybutadiene) 10-40 (e.g.,25.5) hydroxy-terminated polybutadiene (e.g., 1-10 (e.g., 2.5) Poly BdR20LM) Peptizer (e.g., Struktol A60) 1-10 (e.g., 1.8) Silica (e.g.,Hisil 190G) 30-80 (e.g., 49.6) Coupling agent (e.g., SI-69) 1-10 (e.g.,7.25) Antiozonant (e.g., Luxco 2085) 1-10 (e.g., 1.45) Polymerizationaccelerant (e.g., Stearic acid) 1-10 (e.g., 1.45) Plasticizer (e.g.,Tarene 30) 1-10 (e.g., 1.8) Processing additive (e.g., Struktol HT 207)1-10 (e.g., 1.5) Antiozonant (e.g., 6PPD) 1-10 (e.g., 1.7)Polymerization accelerant (e.g., CBS) 1-10 (e.g., 1.6) Polymerizationaccelerant (e.g., TbzTD) 01-1 (e.g., 0.3) Sulfur 0.1-2 (e.g., 0.9)Carbon black (e.g., N-326) 0.1-5 (e.g., 0.7) Vulcanization inhibitor(e.g., PVI) 0.1-5 (e.g., 0.6) Polymerization accelerant (e.g., zincoxide) 1-10 (e.g., 6)

In some specific example embodiments, a wear-resistant rubbercomposition may comprise the following composition, as shown in Table 3(Composition C):

TABLE 3 Composition of Degradable Composition C Material DescriptionParts Per Hundred (Phr) Natural Rubber (e.g., Polyisoprene, SVR10) 30-90(e.g., 65.5) Polybutadiene (e.g., high cis polybutadiene) 10-40 (e.g.,35.4) hydroxy-terminated polybutadiene (e.g., 1-10 (e.g., 6) Poly BdR20LM) Peptizer (e.g., Struktol A60) 1-10 (e.g., 1.6) Silica (e.g.,Hisil 190G) 30-80 (e.g., 55.7) Coupling agent (e.g., SI-69) 1-10 (e.g.,5.5) Antiozonant (e.g., Luxco 2085) 1-10 (e.g., 8.7) Polymerizationaccelerant (e.g., Stearic acid) 1-10 (e.g., 7.5) Plasticizer (e.g.,Tarene 30) 1-10 (e.g., 5) Processing additive (e.g., Struktol HT 207)1-10 (e.g., 5.1) Antiozonant (e.g., 6PPD) 1-10 (e.g., 5.1)Polymerization accelerant (e.g., CBS) 1-10 (e.g., 3.4) Polymerizationaccelerant (e.g., TbzTD) 01-1 (e.g., 0.25) Sulfur 0.1-2 (e.g., 1.5)Carbon black (e.g., N-326) 0.1-5 (e.g., 0.6) Vulcanization inhibitor(e.g., PVI) 0.1-5 (e.g., 2.1) Polymerization accelerant (e.g., zincoxide) 1-10 (e.g., 9)

In some specific example embodiments, a wear-resistant rubbercomposition may comprise the following composition, as shown in Table 4(Composition D):

TABLE 4 Composition of Degradable Composition D Material DescriptionParts Per Hundred (Phr) Natural Rubber (e.g., Polyisoprene, SVR10) 30-90(e.g., 70.5) Polybutadiene (e.g., high cis polybutadiene) 10-40 (e.g.,30.5) hydroxy-terminated polybutadiene (e.g., 1-10 (e.g., 8) Poly BdR20LM) Peptizer (e.g., Struktol A60) 1-10 (e.g., 6) Silica (e.g., Hisil190G) 30-80 (e.g., 45.35) Coupling agent (e.g., SI-69) 1-10 (e.g., 5.5)Antiozonant (e.g., Luxco 2085) 1-10 (e.g., 4.1) Polymerizationaccelerant (e.g., Stearic acid) 1-10 (e.g., 3.1) Plasticizer (e.g.,Tarene 30) 1-10 (e.g., 9) Processing additive (e.g., Struktol HT 207)1-10 (e.g., 4.5) Antiozonant (e.g., 6PPD) 1-10 (e.g., 8.5)Polymerization accelerant (e.g., CBS) 1-10 (e.g., 5.5) Polymerizationaccelerant (e.g., TbzTD) 01-1 (e.g., 4.5) Sulfur 0.1-2 (e.g., 0.5)Carbon black (e.g., N-326) 0.1-5 (e.g., 3.5) Vulcanization inhibitor(e.g., PVI) 0.1-5 (e.g., 3.5) Polymerization accelerant (e.g., zincoxide) 1-10 (e.g., 6.5)

In some specific example embodiments, a wear-resistant rubbercomposition may comprise the following composition, as shown in Table 5(Composition E):

TABLE 5 Composition of Degradable Composition E Material DescriptionParts Per Hundred (Phr) Natural Rubber (e.g., Polyisoprene, SVR10) 30-90(e.g., 85.1) Polybutadiene (e.g., high cis polybutadiene) 10-40 (e.g.,15.4) hydroxy-terminated polybutadiene (e.g., 1-10 (e.g., 3) Poly BdR20LM) Peptizer (e.g., Struktol A60) 1-10 (e.g., 9) Silica (e.g., Hisil190G) 30-80 (e.g., 40.8) Coupling agent (e.g., SI-69) 1-10 (e.g., 5.5)Antiozonant (e.g., Luxco 2085) 1-10 (e.g., 5.52) Polymerizationaccelerant (e.g., Stearic acid) 1-10 (e.g., 5.52) Plasticizer (e.g.,Tarene 30) 1-10 (e.g., 5.4) Processing additive (e.g., Struktol HT 207)1-10 (e.g., 7.1) Antiozonant (e.g., 6PPD) 1-10 (e.g., 4.6)Polymerization accelerant (e.g., CBS) 1-10 (e.g., 6.5) Polymerizationaccelerant (e.g., TbzTD) 01-1 (e.g., 1.1) Sulfur 0.1-2 (e.g., 1.4)Carbon black (e.g., N-326) 0.1-5 (e.g., 3.5) Vulcanization inhibitor(e.g., PVI) 0.1-5 (e.g., 4.4) Polymerization accelerant (e.g., zincoxide) 1-10 (e.g., 8)

In some specific example embodiments, a wear-resistant rubbercomposition may comprise the following composition, as shown in Table 6(Composition F):

TABLE 6 Composition of Degradable Composition F Material DescriptionParts Per Hundred (Phr) Natural Rubber (e.g., Polyisoprene, SVR10) 30-90(e.g., 62.6) Polybutadiene (e.g., high cis polybutadiene) 10-40 (e.g.,37.5) hydroxy-terminated polybutadiene (e.g., 1-10 (e.g., 9.5) Poly BdR20LM) Peptizer (e.g., Struktol A60) 1-10 (e.g., 2) Silica (e.g., Hisil190G) 30-80 (e.g., 35.52) Coupling agent (e.g., SI-69) 1-10 (e.g., 7.5)Antiozonant (e.g., Luxco 2085) 1-10 (e.g., 8.5) Polymerizationaccelerant (e.g., Stearic acid) 1-10 (e.g., 7.6) Plasticizer (e.g.,Tarene 30) 1-10 (e.g., 3.5) Processing additive (e.g., Struktol HT 207)1-10 (e.g., 6.5) Antiozonant (e.g., 6PPD) 1-10 (e.g., 4.3)Polymerization accelerant (e.g., CBS) 1-10 (e.g., 3.5) Polymerizationaccelerant (e.g., TbzTD) 01-1 (e.g., 0.4) Sulfur 0.1-2 (e.g., 1.9)Carbon black (e.g., N-326) 0.1-5 (e.g., 1.4) Vulcanization inhibitor(e.g., PVI) 0.1-5 (e.g., 0.8) Polymerization accelerant (e.g., zincoxide) 1-10 (e.g., 7.5)

In some specific example embodiments, a wear-resistant rubbercomposition may comprise the following composition, as shown in Table 7(Composition G):

TABLE 7 Composition of Degradable Composition G Material DescriptionParts Per Hundred (Phr) Natural Rubber (e.g., Polyisoprene, SVR10) 30-90(e.g., 80.4) Polybutadiene (e.g., high cis polybutadiene) 10-40 (e.g.,10.3) hydroxy-terminated polybutadiene (e.g., 1-10 (e.g., 6) Poly BdR20LM) Peptizer (e.g., Struktol A60) 1-10 (e.g., 1.4) Silica (e.g.,Hisil 190G) 30-80 (e.g., 45.6) Coupling agent (e.g., SI-69) 1-10 (e.g.,5.4) Antiozonant (e.g., Luxco 2085) 1-10 (e.g., 1.4) Polymerizationaccelerant (e.g., Stearic acid) 1-10 (e.g., 5.2) Plasticizer (e.g.,Tarene 30) 1-10 (e.g., 5) Processing additive (e.g., Struktol HT 207)1-10 (e.g., 4.05) Antiozonant (e.g., 6PPD) 1-10 (e.g., 3.52)Polymerization accelerant (e.g., CBS) 1-10 (e.g., 6.5) Polymerizationaccelerant (e.g., TbzTD) 01-1 (e.g., 0.9) Sulfur 0.1-2 (e.g., 1.3)Carbon black (e.g., N-326) 0.1-5 (e.g., 1.4) Vulcanization inhibitor(e.g., PVI) 0.1-5 (e.g., 0.4) Polymerization accelerant (e.g., zincoxide) 1-10 (e.g., 8)

In some specific example embodiments, a wear-resistant rubbercomposition may comprise the following composition, as shown in Table 8(Composition H):

TABLE 8 Composition of Degradable Composition H Material DescriptionParts Per Hundred (Phr) Natural Rubber (e.g., Polyisoprene, SVR10) 30-90(e.g., 55.5) Polybutadiene (e.g., high cis polybutadiene) 10-40 (e.g.,45.8) hydroxy-terminated polybutadiene (e.g., 1-10 (e.g., 3.5) Poly BdR20LM) Peptizer (e.g., Struktol A60) 1-10 (e.g., 2.7) Silica (e.g.,Hisil 190G) 30-80 (e.g., 44.8) Coupling agent (e.g., SI-69) 1-10 (e.g.,5.4) Antiozonant (e.g., Luxco 2085) 1-10 (e.g., 3.3) Polymerizationaccelerant (e.g., Stearic acid) 1-10 (e.g., 6.4) Plasticizer (e.g.,Tarene 30) 1-10 (e.g., 2.6) Processing additive (e.g., Struktol HT 207)1-10 (e.g., 3.3) Antiozonant (e.g., 6PPD) 1-10 (e.g., 4.5)Polymerization accelerant (e.g., CBS) 1-10 (e.g., 8.4) Polymerizationaccelerant (e.g., TbzTD) 01-1 (e.g., 0.6) Sulfur 0.1-2 (e.g., 1.4)Carbon black (e.g., N-326) 0.1-5 (e.g., 0.8) Vulcanization inhibitor(e.g., PVI) 0.1-5 (e.g., 4.4) Polymerization accelerant (e.g., zincoxide) 1-10 (e.g., 10)

In some specific example embodiments, a wear-resistant rubbercomposition may comprise the following composition, as shown in Table 9(Composition I):

TABLE 9 Composition of Degradable Composition I Material DescriptionParts Per Hundred (Phr) Natural Rubber (e.g., Polyisoprene, SVR10) 30-90(e.g., 83.03) Polybutadiene (e.g., high cis polybutadiene) 10-40 (e.g.,16.97) hydroxy-terminated polybutadiene (e.g., 1-10 (e.g., 4) Poly BdR20LM) Peptizer (e.g., Struktol A60) 1-10 (e.g., 2) Silica (e.g., Hisil190G) 30-80 (e.g., 60.58) Coupling agent (e.g., SI-69) 1-10 (e.g., 6.58)Antiozonant (e.g., Luxco 2085) 1-10 (e.g., 1.52) Polymerizationaccelerant (e.g., Stearic acid) 1-10 (e.g., 1.52) Plasticizer (e.g.,Tarene 30) 1-10 (e.g., 2) Processing additive (e.g., Struktol HT 207)1-10 (e.g., 2.05) Antiozonant (e.g., 6PPD) 1-10 (e.g., 1.52)Polymerization accelerant (e.g., CBS) 1-10 (e.g., 1.5) Polymerizationaccelerant (e.g., TbzTD) 01-1 (e.g., 0.2) Sulfur 0.1-2 (e.g., 0.7)Carbon black (e.g., N-326) 0.1-5 (e.g., 1) Vulcanization inhibitor(e.g., PVI) 0.1-5 (e.g., 0.5) Polymerization accelerant (e.g., zincoxide) 1-10 (e.g., 5)

In some specific example embodiments, a wear-resistant rubbercomposition may comprise the following composition, as shown in Table 10(Composition J):

TABLE 10 Composition of Degradable Composition J Material DescriptionParts Per Hundred (Phr) Natural Rubber (e.g., Polyisoprene, SVR10) 30-90(e.g., 56.56) Polybutadiene (e.g., high cis polybutadiene) 10-40 (e.g.,39.4) hydroxy-terminated polybutadiene (e.g., 1-10 (e.g., 9) Poly BdR20LM) Peptizer (e.g., Struktol A60) 1-10 (e.g., 6) Silica (e.g., Hisil190G) 30-80 (e.g., 44) Coupling agent (e.g., SI-69) 1-10 (e.g., 4.83)Antiozonant (e.g., Luxco 2085) 1-10 (e.g., 6.6) Polymerizationaccelerant (e.g., Stearic acid) 1-10 (e.g., 4.5) Plasticizer (e.g.,Tarene 30) 1-10 (e.g., 3.4) Processing additive (e.g., Struktol HT 207)1-10 (e.g., 4.8) Antiozonant (e.g., 6PPD) 1-10 (e.g., 3.3)Polymerization accelerant (e.g., CBS) 1-10 (e.g., 2.8) Polymerizationaccelerant (e.g., TbzTD) 01-1 (e.g., 0.1) Sulfur 0.1-2 (e.g., 1.7)Carbon black (e.g., N-326) 0.1-5 (e.g., 3) Vulcanization inhibitor(e.g., PVI) 0.1-5 (e.g., 0.9) Polymerization accelerant (e.g., zincoxide) 1-10 (e.g., 3)

In some specific example embodiments, a wear-resistant rubbercomposition may comprise the following composition, as shown in Table 11(Composition K):

TABLE 11 Composition of Degradable Composition K Material DescriptionParts Per Hundred (Phr) Natural Rubber (e.g., Polyisoprene, SVR10) 30-90(e.g., 57.14) Polybutadiene (e.g., high cis polybutadiene) 20-50 (e.g.,42.9) Antidegradant (e.g., TMQ) 0.1-2 (e.g., 0.7) Antiozonant (e.g.,Luxco 2085) 1-10 (e.g., 1) Polymerization accelerant (e.g., Stearicacid) 1-10 (e.g., 2.0) Processing additive (e.g., Raffex 90) 5-15 (e.g.,10.5) Antiozonant (e.g., 6PPD) 0.1-1.5 (e.g., 0.74) Sulfur 0.1-2 (e.g.,1.5) Carbon black (e.g., N-234) 30-70 (e.g., 55.7) Antioxidant (e.g.,methyl methacrylate 0.1-5 (e.g., 1.2) butadiene styrene) Polymerizationaccelerant (e.g., zinc oxide) 1-10 (e.g., 3)

In some specific example embodiments, a wear-resistant rubbercomposition may comprise the following composition, as shown in Table 12(Composition L):

TABLE 12 Composition of Degradable Composition L Material DescriptionParts Per Hundred (Phr) Natural Rubber (e.g., Polyisoprene, SVR10) 30-90(e.g., 50.6) Polybutadiene (e.g., high cis polybutadiene) 20-50 (e.g.,46.4) Antidegradant (e.g., TMQ) 0.1-2 (e.g., 0.9) Antiozonant (e.g.,Luxco 2085) 1-10 (e.g., 2.5) Polymerization accelerant (e.g., Stearicacid) 1-10 (e.g., 3.5) Processing additive (e.g., Raffex 90) 5-15 (e.g.,5.4) Antiozonant (e.g., 6PPD) 0.1-1.5 (e.g., 1.4) Sulfur 0.1-2 (e.g.,0.9) Carbon black (e.g., N-234) 30-70 (e.g., 45.3) Antioxidant (e.g.,methyl methacrylate 0.1-5 (e.g., 2.2) butadiene styrene) Polymerizationaccelerant (e.g., zinc oxide) 1-10 (e.g., 2.6)

In some embodiments, a wear-resistant rubber composition, after curing,may have a Shore A hardness of, at least about 15, or at least about 20,or at least about 25, or at least about 30, or at least about 35, or atleast about 40. In some embodiments, a wear-resistant rubbercomposition, after curing and substantially swelling, may have a Shore Ahardness of at least about 20, or about 25, or about 30.

Wear Resistance

In some embodiments, a wear-resistant rubber composition may resist wearcomprising fretting wear, erosive wear, oxidation wear, corrosion wear,or combinations thereof. A wear-resistant rubber composition may resistwear over a period of time, the period of time comprising at least about1 week, at least about 2 weeks, at least about 3 weeks, at least about 4weeks, at least about 6 weeks, at least about 8 weeks, at least about 10weeks, at least about 12 weeks, at least about 14 weeks, at least about16 weeks, at least about 18 weeks, at least about 20 weeks, at leastabout 22 weeks, at least about 24 weeks, at least about 26 weeks, atleast about 28 weeks, and at least about 30 weeks. In some embodiments,“about,” as used in the preceding sentence, includes plus or minus 1week. According to some embodiments, a wear-resistant rubber compositionmay wear at most about 1%, or at most about 2%, or at most about 5%, orat most about 10%, or at most about 15%, or at most about 20%, or atmost about 25%, or at most about 30%, or at most about 35%, or at mostabout 40%, or at most about 45%, or at most about 50%. In someembodiments, a wear-resistant rubber composition may wear at most about10% in about four weeks, or at most about 20% in about four weeks, or atmost about 30% in about four weeks. In some embodiments, awear-resistant rubber composition may wear at most about 10% in abouteight weeks, or at most about 20% in about eight weeks, or at most about30% in about eight weeks. In some embodiments, a wear-resistant rubbercomposition may wear at most about 10% in about 12 weeks, or at mostabout 20% in about 12 weeks, or at most about 30% in about 12 weeks. Insome embodiments, a wear-resistant rubber composition may wear at mostabout 10% in about 16 weeks, or at most about 20% in about 16 weeks, orat most about 30% in about 16 weeks. In some embodiments, awear-resistant rubber composition may wear at most about 10% in about 20weeks, or at most about 20% in about 20 weeks, or at most about 30% inabout 20 weeks. In some embodiments, a wear-resistant rubber compositionmay wear at most about 10% in about 24 weeks, or at most about 20% inabout 24 weeks, or at most about 30% in about 24 weeks. According tosome embodiments, wear resistance may be assessed using the materialloss in weight over the certain period of time the wear-resistant rubbercomposition (e.g., lifter bar) is in use. An initial weight of awear-resistant rubber composition (e.g., lifter bar) may be comparedwith a final weight of the wear-resistant rubber composition to providea wear in weight loss over a period of time, for example a 24 weekperiod. In some embodiments, a percentage wear is calculated by taking aweight remaining at the end of a specified test period and divided theweight remaining at the end of the specified test period by weight atthe beginning of the specified test period, and then multiplying thatvalue by 100%. According to some embodiments, a lifter bar percentagewear is calculated by taking a weight of said lifter bar remaining atthe end of a specified test period and divided the weight of said lifterbar remaining at the end of the specified test period by weight of saidlifter bar at the beginning of the specified test period, and thenmultiplying that value by 100%. In some embodiments, wear of rubbermaterial may be achieved or simulated by any suitable means includingany standardized test method (e.g., tests promulgated by the AmericanNational Standards Institute, ASTM International, or similarorganizations). For example, wear of a lifter bar may be induced bycontinuous, sustained, periodic, intermittent, or other high intensityimpact from larger material (e.g., milled material and mill balls) asthe mill spins. In some embodiments, wear-resistance, shock absorption,and dampening properties of a wear-resistant rubber composition maycontribute (e.g., separately or in combination) to improvements in wearperformance of a wear-resistant rubber composition (e.g., lifter bar).

Lifter Bar Assemblies

A grinding mill, according to some embodiments, may comprise a generallycylindrical drum with openings at one and/or both ends of the drum, atleast one lifter bar assembly spaced about the inside wall of the drum,and at least one mill liner. In some embodiments, a grinding mill mayfurther comprise at least one steel ball. In some embodiments, a typicalgrinding mill may further comprise a substance to be milled, wherein asa drum of the grinding mill is rotated, at least one lifter bar assemblylifts the substance to be milled and at least one steel ball. At somepoint during rotation of a drum, a substance to be milled and at leastone steel ball displaces from at least one lifter bar assembly, whereinthe substance to be milled may impact on at least one surface, the atleast one surface comprising the at least one steel ball, the substanceto be milled, the at least one lifter bar assembly, at least one millliner, a cylindrical drum, or combinations thereof. As a lifter barassembly is used in a grinding mill, the lifter bar assembly may wear. Alifter bar assembly may wear while being used in other mining industryprocesses. Lifter bar assemblies that become worn may have to bereplaced, which may increase logistical and financial burdens on themining and/or milling processes. In some embodiments, a mill liner maywear while being used in a milling process.

According to some embodiments, a lifter bar assembly may comprise atleast one rack for fixing the wear resistant lifter bar to a cylindricalwall of a rotating drum of a mill and at least one wear body comprisinga wear-resistant rubber composition. In some embodiments, a lifter barassembly comprising a wear-resistant rubber composition may wearsignificant less than a lifter bar assembly differing only in that thelifter bar assembly does not comprise at wear-resistant rubbercomposition.

A lifter bar assembly comprising a wear-resistant rubber composition mayresist wear over a period of time, the period of time comprising atleast about 1 week, at least about 2 weeks, at least about 3 weeks, atleast about 4 weeks, at least about 6 weeks, at least about 8 weeks, atleast about 10 weeks, at least about 12 weeks, at least about 14 weeks,at least about 16 weeks, at least about 18 weeks, at least about 20weeks, at least about 22 weeks, at least about 24 weeks, at least about26 weeks, at least about 28 weeks, and at least about 30 weeks. In someembodiments, “about,” as used in the preceding sentence, includes plusor minus 1 week. According to some embodiments, a lifter bar assemblycomprising a wear-resistant rubber composition may wear at most about1%, or at most about 2%, or at most about 5%, or at most about 10%, orat most about 15%, or at most about 20%, or at most about 25%, or atmost about 30%, or at most about 35%, or at most about 40%, or at mostabout 45%, or at most about 50%. In some embodiments, a lifter barassembly comprising a wear-resistant rubber composition may wear at mostabout 10% in about four weeks, or at most about 20% in about four weeks,or at most about 30% in about four weeks. In some embodiments, a lifterbar assembly comprising a wear-resistant rubber composition may wear atmost about 10% in about eight weeks, or at most about 20% in about eightweeks, or at most about 30% in about eight weeks. In some embodiments, alifter bar assembly comprising a wear-resistant rubber composition maywear at most about 10% in about 12 weeks, or at most about 20% in about12 weeks, or at most about 30% in about 12 weeks. In some embodiments, alifter bar assembly comprising a wear-resistant rubber composition maywear at most about 10% in about 16 weeks, or at most about 20% in about16 weeks, or at most about 30% in about 16 weeks. In some embodiments, alifter bar assembly comprising a wear-resistant rubber composition maywear at most about 10% in about 20 weeks, or at most about 20% in about20 weeks, or at most about 30% in about 20 weeks. In some embodiments, alifter bar assembly comprising a wear-resistant rubber composition maywear at most about 10% in about 24 weeks, or at most about 20% in about24 weeks, or at most about 30% in about 24 weeks.

According to some embodiments, a mill liner may comprise at least onerack for fixing the wear resistant lifter bar to a cylindrical wall of arotating drum of a mill and at least one wear body comprising awear-resistant rubber composition. In some embodiments, a mill linercomprising a wear-resistant rubber composition may wear significant lessthan a mill liner differing only in that the mill liner does notcomprise at wear-resistant rubber composition.

A mill liner comprising a wear-resistant rubber composition may resistwear over a period of time, the period of time comprising at least about1 week, at least about 2 weeks, at least about 3 weeks, at least about 4weeks, at least about 6 weeks, at least about 8 weeks, at least about 10weeks, at least about 12 weeks, at least about 14 weeks, at least about16 weeks, at least about 18 weeks, at least about 20 weeks, at leastabout 22 weeks, at least about 24 weeks, at least about 26 weeks, atleast about 28 weeks, and at least about 30 weeks. In some embodiments,“about,” as used in the preceding sentence, includes plus or minus 1week. According to some embodiments, a mill liner comprising awear-resistant rubber composition may wear at most about 1%, or at mostabout 2%, or at most about 5%, or at most about 10%, or at most about15%, or at most about 20%, or at most about 25%, or at most about 30%,or at most about 35%, or at most about 40%, or at most about 45%, or atmost about 50%. In some embodiments, a mill liner comprising awear-resistant rubber composition may wear at most about 10% in aboutfour weeks, or at most about 20% in about four weeks, or at most about30% in about four weeks. In some embodiments, a mill liner comprising awear-resistant rubber composition may wear at most about 10% in abouteight weeks, or at most about 20% in about eight weeks, or at most about30% in about eight weeks. In some embodiments, a mill liner comprising awear-resistant rubber composition may wear at most about 10% in about 12weeks, or at most about 20% in about 12 weeks, or at most about 30% inabout 12 weeks. In some embodiments, a mill liner comprising awear-resistant rubber composition may wear at most about 10% in about 16weeks, or at most about 20% in about 16 weeks, or at most about 30% inabout 16 weeks. In some embodiments, a mill liner comprising awear-resistant rubber composition may wear at most about 10% in about 20weeks, or at most about 20% in about 20 weeks, or at most about 30% inabout 20 weeks. In some embodiments, a mill liner comprising awear-resistant rubber composition may wear at most about 10% in about 24weeks, or at most about 20% in about 24 weeks, or at most about 30% inabout 24 weeks.

Wear-Resistant Shock Absorbers

According to some embodiments, a shock absorber and/or damper may dampshock impulses. In some embodiments, a shock absorber may comprise atleast one wear-resistant rubber composition. A shock absorber comprisingat least one wear-resistant rubber composition may wear less than ashock absorber not comprising at least one wear-resistant rubbercomposition, according to some embodiments.

A shock absorber comprising a wear-resistant rubber composition mayresist wear over a period of time, the period of time comprising atleast about 1 week, at least about 2 weeks, at least about 3 weeks, atleast about 4 weeks, at least about 6 weeks, at least about 8 weeks, atleast about 10 weeks, at least about 12 weeks, at least about 14 weeks,at least about 16 weeks, at least about 18 weeks, at least about 20weeks, at least about 22 weeks, at least about 24 weeks, at least about26 weeks, at least about 28 weeks, and at least about 30 weeks. In someembodiments, “about,” as used in the preceding sentence, includes plusor minus 1 week. According to some embodiments, a shock absorbercomprising a wear-resistant rubber composition may wear at most about1%, or at most about 2%, or at most about 5%, or at most about 10%, orat most about 15%, or at most about 20%, or at most about 25%, or atmost about 30%, or at most about 35%, or at most about 40%, or at mostabout 45%, or at most about 50%. In some embodiments, a shock absorbercomprising a wear-resistant rubber composition may wear at most about10% in about four weeks, or at most about 20% in about four weeks, or atmost about 30% in about four weeks. In some embodiments, a shockabsorber comprising a wear-resistant rubber composition may wear at mostabout 10% in about eight weeks, or at most about 20% in about eightweeks, or at most about 30% in about eight weeks. In some embodiments, ashock absorber comprising a wear-resistant rubber composition may wearat most about 10% in about 12 weeks, or at most about 20% in about 12weeks, or at most about 30% in about 12 weeks. In some embodiments, ashock absorber comprising a wear-resistant rubber composition may wearat most about 10% in about 16 weeks, or at most about 20% in about 16weeks, or at most about 30% in about 16 weeks. In some embodiments, ashock absorber comprising a wear-resistant rubber composition may wearat most about 10% in about 20 weeks, or at most about 20% in about 20weeks, or at most about 30% in about 20 weeks. In some embodiments, ashock absorber comprising a wear-resistant rubber composition may wearat most about 10% in about 24 weeks, or at most about 20% in about 24weeks, or at most about 30% in about 24 weeks.

It is understood that the listed apparatuses for each unit are forillustration purposes only, and this is not intended to limit the scopeof the application. A specific combination of these or other apparatusesor units can be configured in such a system for the intended use basedon the teachings in the application.

Persons skilled in the art may make various changes in the shape, size,number, separation characteristic, and/or arrangement of parts withoutdeparting from the scope of the instant disclosure. Persons skilled inthe art may make various changes in the kind, number, and/or arrangementof R-groups, substituents, and/or heteroatoms without departing from thescope of the instant disclosure. Each disclosed method and method stepmay be performed in association with any other disclosed method ormethod step and in any order according to some embodiments. Where theverb “may” appears, it is intended to convey an optional and/orpermissive condition, but its use is not intended to suggest any lack ofoperability unless otherwise indicated. Persons skilled in the art maymake various changes in methods of preparing and using a composition,device, and/or system of the disclosure. Where desired, some embodimentsof the disclosure may be practiced to the exclusion of otherembodiments.

Also, where ranges have been provided, the disclosed endpoints may betreated as exact and/or approximations as desired or demanded by theparticular embodiment. Where the endpoints are approximate, the degreeof flexibility may vary in proportion to the order of magnitude of therange. For example, on one hand, a range endpoint of about 50 in thecontext of a range of about 5 to about 50 may include 50.5, but not 52.5or 55 and, on the other hand, a range endpoint of about 50 in thecontext of a range of about 0.5 to about 50 may include 55, but not 60or 75. In addition, it may be desirable, in some embodiments, to mix andmatch range endpoints. Also, in some embodiments, each figure disclosed(e.g., in one or more of the examples, tables, and/or drawings) may formthe basis of a range (e.g., depicted value +/−about 10%, depicted value+/−about 50%, depicted value +/−about 100%) and/or a range endpoint.With respect to the former, a value of 50 depicted in an example, table,and/or drawing may form the basis of a range of, for example, about 45to about 55, about 25 to about 100, and/or about 0 to about 100.

These equivalents and alternatives along with obvious changes andmodifications are intended to be included within the scope of thepresent disclosure. Accordingly, the foregoing disclosure is intended tobe illustrative, but not limiting, of the scope of the disclosure asillustrated by the appended claims.

The title, abstract, background, and headings are provided in compliancewith regulations and/or for the convenience of the reader. They includeno admissions as to the scope and content of prior art and nolimitations applicable to all disclosed embodiments.

EXAMPLES

Some specific example embodiments of the disclosure may be illustratedby one or more of the examples provided herein.

Example 1 Degradable Test Formulas

Nine wear-resistant rubber compositions were created using varyingpolymer distributions to compare the difference in rheological andphysical properties (Table 13). Concentrations of hydroxy-terminatedpolybutadiene were varied in each sample, wherein a control sample with0 Phr hydroxy-terminated polybutadiene (Liq. PBD) was compared to eightother wear-resistant rubber compositions with incrementally increasingconcentrations of hydroxy-terminated polybutadiene. The range ofhydroxy-terminated polybutadiene consists of 0 Phr, 1 Phr, 2 Phr, 3 Phr,4, Phr, 5 Phr, 6 Phr, 7 Phr, and 8 Phr.

TABLE 13 Rheometer MDR Data for the Nine Compositions Tested Control 2A2B 2C 2D 2E 2F 2G 2H 0 Phr 1Phr 2Phr 3Phr 4Phr 5Phr 6Phr 7Phr 8Phr Liq.Liq. Liq. Liq. Liq. Liq. Liq. Liq. Liq. Specification PBD PBD PBD PBDPBD PBD PBD PBD PBD Rheometer MDR, 4 minutes @ 350° F., 1° Arc ML, lb-in3.50-5.50  3.49  3.70  4.04  3.76  3.85  3.72  3.52  3.63  3.53 Ts2, m:s0:50-1:30 0:59 0:49 0:53 1:08 0:56 0:59 0:59 1:01 1:04 TC90, m:s2:30-3:30 3:10 3:10 3:08 3:13 3:13 3:13 3:14 3:14 3:13 MH, lb-in20.50-27.00 22.67 23.06 23.17 20.53 20.99 19.77 19.46 19.21 18.25

Rheometer data for an MH value is illustrated in Table 13 as well as inFIG. 1. FIG. 2 illustrates an increasing and then decreasing trend lineof MH values when comparing wear-resistant rubber compositions in theorder of control, 2A, 2B, 2C, 2D, 2E, 2F, 2G, and then 2H.

Physical tensile and tear properties were measured per standard cureconditions for the nine wear-resistant rubber compositions. The data canbe found in table 14.

TABLE 14 Tensile and Tear Data Samples Cured for 30 minutes at 280° F.Control 2A 2B 2C 2D 2E 2F 2G 2H 0 Phr 1Phr 2Phr 3Phr 4Phr 5Phr 6Phr 7Phr8Phr Liq. Liq. Liq. Liq. Liq. Liq. Liq. Liq. Liq. Specification PBD PBDPBD PBD PBD PBD PBD PBD PBD Shore A   65 ± 5 65 65 66 62 64 63 62 63 61Sp. Gr. 1.18 ± 5 1.18 1.17 1.17 1.18 1.16 1.16 1.16 1.16 1.16 Tear C,lbf/in 500+ 682 724 633 551 663 684 600 574 533 Tensile, PSI 3200+  36533856 3968 3611 3949 3716 3650 3764 3636 Elongation, % 500+ 759 758 8151002 994 906 807 704 753 100% Mod, PSI — 247 285 288 234 264 263 226 251246 200% Mod, PSI — 509 626 599 449 579 549 445 580 532 300% Mod, PSI —958 1154 1098 859 1004 986 750 1080 992

Hardness data for each wear-resistant rubber composition was measuredand a comparison of the data is illustrated in FIG. 3. Similarly,tensile strength for each wear-resistant rubber composition was measuredand a comparison of the data is illustrated in FIG. 4. FIG. 5illustrates elongation measurement values across the wear-resistantrubber compositions with various hydroxy-terminated polybutadieneconcentrations.

Example 2

FIG. 6A illustrates a lifter bar assembly wear testing performed on aperiod of four weeks on lifter bars comprising a wear-resistant rubbercomposition according to Compositions K and L. In FIG. 6A, a lifter barassembly (e.g., 500, 530) comprising a rack (e.g., 570), an unexposedportion (e.g., 580), an exposed portion (e.g., 560), wherein the lifterbar assembly shows wear at 0 weeks (e.g., 510, 540) and wear at 4 weeks(e.g., 520, 550).

FIG. 6B illustrates a lifter bar assembly wear testing performed on aperiod of four weeks on lifter bars comprising wear-resistant rubbercomposition according to Compositions A through J. In FIG. 6A, a lifterbar assembly (e.g., 500, 530) comprising a rack (e.g., 570), anunexposed portion (e.g., 580), an exposed portion (e.g., 560), whereinthe lifter bar assembly shows wear at 0 weeks (e.g., 510, 540) and wearat 4 weeks (e.g., 520, 550). Over the duration of the lifter barassembly wear testing, the lifter bars of FIG. 6A, wherein the lifterbars comprised a wear-resistant rubber composition not comprising atleast one hydroxy-terminated polybutadiene, wore to a great extent thanthe lifter bars of FIG. 6B, wherein the lifter bars comprised awear-resistant rubber composition comprising at least onehydroxy-terminated polybutadiene. Levels of wear can be attained bymeasuring the difference between the wear at 0 weeks (e.g., 510, 540)and wear at 4 weeks (e.g., 520, 550). The difference between the wear at0 weeks (e.g., 510, 540) and wear at 4 weeks (e.g., 520, 550) for lifterbars according to Compositions K and L are greater than the differencebetween the wear at 0 weeks (e.g., 510, 540) and wear at 4 weeks (e.g.,520, 550) for lifter bars according to Compositions A through J.

Example 3 Specific Example Embodiments of a Wear-Resistant RubberComposition

A wear-resistant rubber composition may be configured to have one ormore of the desired qualities disclosed in this application including,for example, abrasion resistance, wear resistance, density ofcrosslinking, tolerance of salinity, curing temperature, among others,by adjusting the composition of one or more components. Examples ofwear-resistant rubber compositions are provided in Table 15.

TABLE 15 Wear-resistant Rubber Compositions Formulation (wt. %) A B C DE F G H I J K L M N O P A natural rubber 35.4 41.5 46.8 43.5 50.4 49.138.9 39.8 52.2 40.8 30.6 43.5 46.4 45.9 47.4 42.9 A polybutadiene 11.32.4 5.6 8.9 7.5 5.4 14.3 9.1 6.5 9.2 9.7 7.4 7.3 11.8 3.4 7.6 A peptizer0.5 0.7 0.1 1.0 0.5 0.7 1.1 0.6 0.6 1.9 0.8 1 1.3 1.7 1 0.8 Ahydroxy-terminated 1.2 9 4.3 2.1 3.3 4.7 5.1 3.6 3.9 4.8 6.5 7.2 1.6 2.41.9 2 polybutadiene A silica 25.4 32.3 25.6 31.8 25.1 24.9 25.6 33.322.6 30.8 40.2 25.7 29.8 25.1 25.9 36.2 A coupling agent 2.1 1.9 1 3.53.9 4.5 2.9 3.3 6.1 2.6 2.2 6.1 3.3 4.5 10 2.1 A first antiozonant 2 1.40.9 0.8 0.6 1 0.7 0.4 0.3 0.5 0.5 0.3 1.1 0.6 0.6 0.3 A firstpolymerization 1.6 0.7 2 0.8 0.1 0.7 0.4 0.3 0.2 0.7 0.3 0.2 0.9 0.2 0.10.5 accelerant A plasticizer 1.8 1.1 1.1 1.0 0.6 1.3 1.9 0.1 0.4 0.9 0.10.6 1 0.1 0.4 1.5 A processing additive 4.7 0.8 1.9 1.1 1.6 1.6 3 3 2.33.4 3.3 1.5 3.3 3.3 3.3 1.9 A second antiozonant 1.9 1 1.9 0.8 0.9 1.30.9 0.5 0.1 0.4 0.4 0.2 0.4 0.5 0.6 0.6 A second polymerization 1.8 1.41.6 0.8 1.6 0.6 0.4 0.3 0.5 0.6 0.3 1.2 0.3 0.1 0.8 0.5 accelerant Athird polymerization 0.6 1.6 1.1 0.1 0.7 0.2 1.6 0.4 0.6 0.3 0.6 0.8 0.10.3 0.2 0.3 accelerant A sulfur 0.9 1.1 0.6 0.4 0.9 0.6 0.9 0.2 0.1 0.41.1 0.6 0.5 0.4 0.3 0.6 A carbon black 1.8 0.9 0.4 0.5 0.8 1.1 0.8 0.60.4 0.2 0.6 0.1 0.2 0.8 0.4 0.4 A vulcanization inhibitor 2 0.6 1.3 0.30.5 0.7 0.4 0.1 0.6 0.6 0.2 0.3 0.3 0.2 0.8 0.2 A fourth polymerization5 1.6 3.8 2.6 1 1.6 1.1 4.4 2.6 1.9 2.6 3.3 2.2 2.1 2.9 1.6 accelerant

Example 4

A method for determining an effective cross-linking density of awear-resistant rubber composition can be found in Martin Jr, Donald L.Crosslink Density Determinations for Polymeric Materials. No.RK-TR-70-6. ARMY MISSILE RESEARCH DEVELOPMENT AND ENGINEERING LABREDSTONE ARSENAL AL PROPULSION DIRECTORATE, 1970. For example, awear-resistant rubber composition sample with an approximately ¾ inchoutside diameter, ½ inch inside diameter, and ¼ inch wide (unswollencondition) was produced. The mass of the sample was recorded. Using asoxhlet extraction device, a wear-resistant rubber composition samplewas swelled for 24 hours at 120° F. using the solvent tetrahydrofuran.After swelling, tensile and compression measurements were obtained at acrosshead displacement rate of 0.02 inch per minute, wherein the samplesare submerged in solvent during the test. The data obtained was used tocalculate effective crosslinking densities.

What is claimed is:
 1. A wear-resistant rubber composition comprising:at least one hydroxy-terminated polybutadiene; at least one naturalrubber; at least one polymerization accelerant; at least one sulfur; atleast one polybutadiene; at least one silica; and at least one silane,wherein the wear-resistant rubber composition has an effectivecross-linking density of at least about 30×10⁻⁵ moles/cm³.
 2. Thewear-resistant rubber composition of claim 1, further comprising anycombination of: an antiozonant; a vulcanization inhibitor; a processingadditive; and a coupling agent.
 3. The wear-resistant rubber compositionof claim 2, further comprising any combination of: an organosilaneadditive; a peptizer; a plasticizer; and a carbon black.
 4. Thewear-resistant rubber composition of claim 2, wherein the at least onenatural rubber is present at a concentration ranging from about 20 wt. %to about 70 wt. % of the wear-resistant rubber composition, and furtherwherein one or more of: the at least one polymerization accelerant isselected from the group consisting of zinc oxide, stearic acid,N-cyclohexyl-2-benzothiazole sulfonamide, and tetrabenzyl thiuramdisulfide; the at least one hydroxy-terminated polybutadiene is presentat a concentration ranging from about 1 wt. % to about 10 wt. % of thewear-resistant rubber composition; and the at least one processingadditive is present at a concentration ranging from about 1 wt. % toabout 10 wt. % of the wear-resistant rubber composition.
 5. Thewear-resistant rubber composition of claim 1, wherein the at least onehydroxy-terminated polybutadiene is present at a concentration of about2 wt. % of the wear-resistant rubber composition.
 6. The wear-resistantrubber composition of claim 1, wherein the at least one polybutadiene ispresent at a concentration ranging from about 2 wt. % to about 20 wt. %of the wear-resistant rubber composition.
 7. The wear-resistant rubbercomposition of claim 1, wherein the wear-resistant rubber compositionmay be used in a wear-resistant lifter bar assembly.
 8. Thewear-resistant rubber composition of claim 1, wherein the wear-resistantrubber composition has an effective cross-linking density of at leastabout 55×10⁻⁵ moles/cm³.
 9. The wear-resistant rubber composition ofclaim 1, wherein the wear-resistant rubber composition wears at mostabout 30% over about 24 weeks.
 10. A wear-resistant rubber compositioncomprising: at least one hydroxy-terminated polybutadiene; at least onenatural rubber; at least one polymerization accelerant; at least onesulfur; at least one polybutadiene; at least one silica; and at leastone silane, wherein the wear-resistant rubber composition has aneffective cross-linking density of at least about 30×10⁻⁵ moles/cm³, andwherein the wear-resistant rubber composition wears from about 10% toabout 40% over a period of time, the period of time selected from thegroup consisting of about 1 week, about 3 weeks, about 7 weeks, about 14weeks, about 21 weeks, and about 24 weeks.
 11. The wear-resistant rubbercomposition of claim 10, further comprising any combination of: anantiozonant; a vulcanization inhibitor; a processing additive; and acoupling agent.
 12. The wear-resistant rubber composition of claim 11,wherein the wear-resistant rubber composition may be used in awear-resistant lifter bar assembly.
 13. The wear-resistant rubbercomposition of claim 10, further comprising any combination of: anorganosilane additive; a peptizer; a plasticizer; and a carbon black.14. The wear resistant rubber composition of claim 13, wherein thewear-resistant rubber composition wears at most about 30% over about 24weeks.
 15. A wear-resistant lifter bar assembly comprising: at least onerack for fixing the wear resistant lifter bar to a cylindrical wall of arotating drum of a mill; and at least one wear body comprising a wearresistant rubber composition, wherein the wear resistant rubbercomposition comprises: at least one hydroxy-terminated polybutadiene; atleast one natural rubber; at least one polymerization accelerant; atleast one sulfur; at least one polybutadiene; at least one silica; andat least one silane, wherein the wear-resistant rubber composition hasan effective cross-linking density of at least about 30×10⁻⁵ moles/cm³.16. The wear-resistant lifter bar assembly of claim 15, wherein the wearresistant rubber composition further comprises any combination of: anantiozonant; a vulcanization inhibitor; a processing additive; and acoupling agent.
 17. The wear-resistant lifter bar assembly of claim 16,wherein the wear resistant rubber composition further comprises anycombination of: an organosilane additive; a peptizer; a plasticizer; anda carbon black.
 18. The wear-resistant lifter bar assembly of claim 16,wherein the at least one natural rubber is present at a concentrationranging from about 20 wt. % to about 70 wt. % of the wear-resistantrubber composition, and further wherein one or more of: the at least onepolymerization accelerant is selected from the group consisting of zincoxide, stearic acid, N-cyclohexyl-2-benzothiazole sulfonamide, andtetrabenzyl thiuram disulfide; the at least one polybutadiene is presentat a concentration ranging from about 2 wt. % to about 20 wt. % of thewear-resistant rubber composition; and-the at least one processingadditive is present at a concentration ranging from about 1 wt. % toabout 10 wt. % of the wear-resistant rubber composition.
 19. Thewear-resistant lifter bar assembly of claim 15, wherein the at least onehydroxy-terminated polybutadiene is present at a concentration rangingfrom about 1 wt. % to about 10 wt. % of the wear-resistant rubbercomposition.
 20. The wear-resistant lifter bar assembly of claim 15,wherein the at least one hydroxy-terminated polybutadiene is present ata concentration of about 2 wt. % of the wear-resistant rubbercomposition.
 21. The wear-resistant lifter bar assembly of claim 15,wherein the wear-resistant rubber composition has an effectivecross-linking density of at least about 55×10⁻⁵ moles/cm³.
 22. Thewear-resistant lifter bar assembly of claim 15, wherein thewear-resistant rubber composition wears at most about 30% over about 24weeks.